pH triggered site specific targeted controlled drug delivery system for the treatment of cancer

ABSTRACT

The present invention relates to a novel pH triggered, targeted controlled release system. The controlled delivery system of the present invention is substantially a free-flowing powder formed of solid hydrophobic nanospheres comprising pharmaceutical active ingredients that are encapsulated in pH sensitive microspheres. The invention also relates to the processes for preparing the compositions and processes for using same. The controlled release system can be used to target and control the release of active ingredients for treating a cellular proliferation disease or tumors. The invention further pertains to pharmaceutical products comprising the controlled release system of the present invention.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/315,801, filed Dec. 9, 2002, entitled pHTriggered Targeted Controlled Release Systems For The Delivery OfPharmaceutical Active Ingredients, the entirety of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a novel targeted controlled drugdelivery system for the treatment of patients afflicted with oncologicaldisorders, such as cancer tumors. More specifically, the presentinvention relates to a site specific targeted controlled drug deliverycomposition that comprises solid hydrophobic nanospheres encapsulated ina pH sensitive microsphere for treating cancer tumors.

[0004] 2. Description of the Related Art

[0005] Systemic chemotherapy is one of the most successful treatmentsfor cancer out of the current available treatment strategies, includingsurgical resection and external beam radiation therapy and has beensuccessful in treating colon-rectum, esophagus, liver, pancreas, kidney,and melanoma cancers. However, efficacious systemic chemotherapeuticagents at the doses that control tumor growth have high systemictoxicity and adverse side effects such as vomiting, myelosuppression,cardiac toxicity, pulmonary fibrosis, hepatobiliary toxicity, andothers. These toxic side effects are the limiting factor in determiningthe concentration of the drug that can be prescribed to the patient andas a result the doses that are administered may be insufficient tocompletely kill the tumor cells and prevent their spreading andregrowth. Poor solubility and low bioavailability of some of thechemotherapeutic agents were also observed to reduce treatment efficacy.For example, paclitaxel (taxol), a high molecular weight, lipophilicdeterpenoid isolated from the western yew, Taxus brevifolia, isinsoluble in water and needs to be administered intravenously bydilution into saline of the drug dissolved or suspended inpolyoxyethylated castor oil.

[0006] Targeted controlled delivery of the chemotherapeutic agent to thetumor site and the ability to maintain efficacious levels of theseagents at the target site over the duration of treatment has long beenthe goal of the pharmaceutical industry. The aim in this form oftreatment is to deliver higher and more effective doses of thechemotherapeutic agent to the tumor tissue without affecting thesurrounding healthy tissue. If successful, targeted delivery provides asignificant reduction in systemic toxicity, reduction of thechemotherapeutic agent dose, and increased treatment efficacy.

[0007] Liposomes have been widely used as delivery vehicles foranti-cancer drugs. U.S. Pat. No. 6,426,086 discloses a serum ofliposomes that are pH-sensitive for controlled drug delivery. Theliposomes are complexed with a molecule comprising a thermally-sensitivepolymer showing lower critical solution temperature behavior in aqueoussolutions. The thermally-sensitive polymer bears a hydrophobicsubstituent and a pH sensitive substituent, wherein the hydrophobicsubstituent is less than 10 kD and which pH sensitive substituentremains ionizable following the covalent bonding to thethermally-sensitive polymer, and whose pH sensitive does not depend oncleavage of the covalent bond to the thermally-sensitive polymer. Thelimited stability of liposomes both in terms of shelf life and afteradministration, their ability to encapsulate only certain types ofmolecules, as well as their rapid clearance from the blood have hamperedthe use of liposomes as effective controlled drug delivery systems.

[0008] U.S. Pat. No. 6,602,524 discloses methods for treating tumorscomprising the administration of a drug loaded in pH-sensitivemicrospheres wherein said pH-sensitive microspheres comprise across-linked polymer gel comprising ethyl methacrylate, diethylaminoethyl methacrylate, and divinyl benzene. The pH-sensitivemicrospheres have a swelling transition with the pH range found in ornear tumor tissue. When the microspheres swell, the loaded drug isreleased into the microenvironment of the tumor tissue. The microspheresare capable of effectively releasing a loaded substance at apre-determined pH. The major drawback of the pH sensitive microspheresdisclosed in U.S. Pat. No. 6,602,524 is that the matrix structurecreated by the cross-linking of ethyl methacrylate, diethyl aminoethylmethacrylate, and divinyl benzene is most likely to facilitate thediffusion and premature release of the chemotherapeutic agents, that arerelatively small molecules, before these microspheres reach the targetsite of the tumor. Further protection of these molecules is needed toensure that they are sustained by microspheres until they reach thetumor site. Also, at a pre-determined pH these microspheres quicklyrelease the drug and cannot provide prolonged release of these activeagents over an extended period of time.

[0009] The prior art of which applicant is aware does not set forth acontrolled release system for the effective treatment of patientsafflicted with oncological disorders, such as cancer tumors, thateffectively deliver and localize the therapeutic effect ofchemotherapeutic agents to the target site or the tumor tissue andmaintains efficacious levels of these agents at the target site for theduration of treatment. Therefore, there remains a need for a system andmethod of cancer treatment that overcomes the drawbacks of the systemsdisclosed in the prior art and that effectively deliver effectiveconcentrations of chemotherapeutic agent targeting only the tumor tissuewhile reducing the damage to surrounding healthy tissue, and maintainefficacious levels of these agents at the target site for the durationof treatment.

SUMMARY OF THE INVENTION

[0010] The present invention relates to an improved carrier system forsite-specific targeted controlled delivery of pharmaceutical activeingredients onto cancer tumors and maintains efficacious levels of theseagents at the target site for the duration of treatment. Moreparticularly, the invention relates to a controlled release system thatcomprises solid hydrophobic nanospheres encapsulated in a pH sensitivemicrosphere for the treatment of patients afflicted with oncologicaldisorders, such as cancer tumors. Pharmaceutical active ingredients canbe incorporated in the solid hydrophobic nanospheres, in the pHsensitive microsphere, or in both the micro and nanospheres. The activeingredients and the nanospheres are released from the microsphere at thepH range typically found in the surrounding of tumor tissues. At the pHrange typically found in the surrounding of tumor tissues themicrosphere pH sensitive matrix materials dissolve or swell. Thedissolution or swelling of the matrix disrupts the microsphere structureand facilitates the release of the nanospheres and the activeingredients. The deposition of the nanospheres onto the tumor tissue isimproved by optimizing particle size to ensure entrainment of thenanospheres within the target tissue and by modifying the surfaceproperties of the nanospheres to enhance their affinity for a particularresidue expressed on a cell surface or enhance their affinity for a cellsurface protein or receptor to maximize interaction between thenanospheres and the tumor tissue.

[0011] The present invention also pertains to solid hydrophobicnanospheres encapsulated in a pH sensitive microsphere that can beloaded with a pharmaceutical active ingredient useful in treatingcancerous cells. The microspheres are capable of effectively releasing apre-determined pH pharmaceutical active ingredients and the nanospheresloaded with pharmaceutical active ingredients. The nanospheres can bedesigned to release their incorporated pharmaceutical active ingredientsover an extended period of time at a pH that is typically found in ornear cancerous tissue.

[0012] The present invention also provides a method of treating cancertumors comprising administering an effective amount of microspheres thatare capable of enhancing the bioavailability of the pharmaceuticalactive ingredient encapsulated in the solid hydrophobic nanospheres andreleasing the pharmaceutical active ingredient over an extended periodof time at a specified pH.

[0013] In one embodiment, the pH-sensitive microspheres of the presentinvention swell and release the pharmaceutical active ingredients andthe solid hydrophobic nanospheres within a pH range typically found intumor tissue. The compositions and methods of the present inventionprovide a novel treatment of cancer, which specifically targets tumortissue and reduces damage to surrounding healthy tissue.

[0014] The pharmaceutical active ingredient encapsulated in thecontrolled release system of the present invention include, but are notlimited to, cytotoxic agents, chemotherapeutic agents, radionuclides,gene based drugs or gene based treatment modalities, including the useof sense, antisense nucleotide sequences, antigens, antibodies,ribozymes, as well as chimeric oligonucleotides constructs for genecorrection. The pharmaceutical active ingredient may also include DNA orRNA fragments, which code functionally active or inactive orconditionally inactivatable proteins.

[0015] The invention further provides a method to effectively deliverand localize the therapeutic effect of chemotherapeutic agents to thetarget site or tumor tissue and maintain efficacious levels of theseagents at the target site for the duration of treatment, that reducesthe amount of adverse side effects such as vomiting, myelosuppression,cardiac toxicity, pulmonary fibrosis, hepatobiliary toxicity, andpericholangitis commonly associated with other current non-invasivetreatments.

[0016] A preferred embodiment of the present invention pertains to amethod of treating a tumor with the solid hydrophobic nanospheresencapsulated in a pH sensitive microsphere which contain a selectedanti-tumor substance and injecting the microspheres in a blood vesselsuitable for carrying the microspheres to the tumor.

[0017] In one embodiment, the nanospheres of the present invention arebioadhesive. Bioadhesive nanosphere can be created by incorporating abioadhesive material into the solid hydrophobic matrix of thenanospheres, by incorporating a bioadhesive material in the pH-sensitivemicrosphere matrix, or by using a bioadhesive material in the nanospherematrix in conjunction with a bioadhesive material in the microspherematrix.

[0018] The carrier system of the present invention is a free-flowingpowder formed of solid hydrophobic nanospheres comprising various activeingredients that are encapsulated in a pH sensitive microspheres, havingthe advantages of:

[0019] (i) protection of the pharmaceutical active ingredients, duringstorage, or until they reach the target site;

[0020] (ii) pH triggered controlled release of a first pharmaceuticalactive ingredient from the microspheres and of a second pharmaceuticalactive ingredient from the nanospheres at the pH range typically foundin the surrounding of tumor tissues, and,

[0021] (iii) site specific targeted delivery and enhanced deposition ofthe nanospheres comprising pharmaceutical active ingredients, onto thetarget tumor site;

[0022] (iv) enhanced bioavailability and efficacy of pharmaceuticalactive ingredients encapsulated in the nanospheres; and

[0023] (v) prolonged release of pharmaceutical active ingredientsencapsulated in the nanospheres over an extended period of time.

[0024] The invention also provides a method for producing the multicomponent controlled release system of the present invention includingactive ingredients that comprises the steps of:

[0025] (i) incorporating the pharmaceutical active ingredients intosolid hydrophobic nanospheres;

[0026] (ii) forming an aqueous mixture comprising of one or morepharmaceutical active agents, the nanospheres, and pH sensitivematerials; and

[0027] (iii) spray drying the mixture to form a dry powder composition.

[0028] The invention further provides a process for producing the multicomponent controlled release system of the present invention includingthe pharmaceutical active ingredients that comprises the steps of:

[0029] (i) heating hydrophobic materials to a temperature above themelting point of the materials to form a melt;

[0030] (ii) dissolving or dispersing a first pharmaceutical active agentinto the melt;

[0031] (iii) dissolving or dispersing a second pharmaceutical activeagent, pH sensitive material, and a targeting material, in the aqueousphase;

[0032] (iv) heating the composition to above the melting temperature ofthe hydrophobic materials;

[0033] (v) mixing the hot melt with the aqueous phase to form adispersion;

[0034] (vi) high shear homogenization of the dispersion at a temperatureabove the melting temperature until a homogeneous fine dispersion isobtained having a sphere size of from about 1 micron to about 2 microns;

[0035] (vii) cooling the dispersion to ambient temperature; and

[0036] (viii) spray drying the emulsified mixed suspension to form a drypowder composition.

[0037] The invention also provides pharmaceutical products comprisingthe multi component controlled release system of the present invention.

[0038] The invention will be more fully described by reference to thefollowing drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a schematic diagram of the pH sensitive microspheres ofthe present invention

[0040]FIG. 2 is a schematic diagram of the release profile of activeingredients from the controlled release system of the present invention.

[0041]FIG. 3 is a schematic diagram of the nanospheres encapsulated inthe pH sensitive microsphere of the present invention. The surfaceproperties of the nanospheres (shown as squiggly lines) can be alteredto be bioadhesive, negatively charged, or positively charged, dependingon the intended target site.

DETAILED DESCRIPTION

[0042] pH levels in human tumors are substantially and consistentlylower than that in normal tissue (Gerweck L. E. et al., “Cellular pHgradient in tumor versus normal tissue: potential exploitation for thetreatment of cancer”, Cancer Research 56, issue 6, pp. 1194-1198, 1996).Deborah M. P. et al. (“The Relationship between Intracellular andExtracellular pH in Spontaneous Canine Tumors”, Clinical Cancer ResearchVol. 6, pp. 2501-2505, 2000) have also reported that the cellular uptakeof chemotherapeutic drugs may be dependent on the pH gradient betweenthe intracellular and extracellular compartments. Hence, pH-sensitivedelivery systems can be a useful route for tumor targeting. The pHdifference provides an exploitable avenue for targeting thechemotherapeutic agent to the tumor site. Also, weakly acidic drugdelivery systems, which are relatively lipid soluble in their nonionizedstate have been found to diffuse freely across the cell membrane and,upon entering a relatively basic intracellular compartment, becometrapped and accumulate within a cell, leading to substantial differencesin the intracellular/extracellular drug distribution between tumor andnormal tissue for drugs exhibiting appropriate pKas.

[0043] The present invention provides an improved pH triggered,site-specific targeted controlled delivery system for the treatment ofpatients afflicted with conditions associated with or mediated by cellproliferation, e.g., oncological disorders, such as cancer and tumors.The controlled delivery system of the present invention comprises solidhydrophobic nanospheres encapsulated in a pH sensitive microsphere, asshown in FIG. 1. Pharmaceutical active ingredients useful in treatingcancerous cells can be incorporated in the solid hydrophobicnanospheres, in the pH sensitive microsphere, or in both themicrospheres and nanospheres. A first pharmaceutical active ingredientcan be incorporated in the nanosphere and a second pharmaceutical activeingredient, which can be the same or different from the firstpharmaceutical active ingredient, can be incorporated into themicrosphere.

[0044] The compositions and methods of the present invention provide anovel treatment of cell proliferation and the control of cancer,specifically targeting tumor tissue thereby reducing damage tosurrounding tissue. The pH-sensitive microspheres of the presentinvention swell or dissolve within a pH range typically found in tumortissue and effectively release the pharmaceutical active ingredientsfrom the microspheres and the solid hydrophobic nanospheres comprisingthe same or different pharmaceutical active ingredients onto the tumorsite, as shown in FIG. 2. The nanospheres can be designed to releasetheir pharmaceutical active ingredient over an extended period of timeat a pH that is typically found in or near cancerous tissue and maintainefficacious levels of these agents at the target site for the durationof treatment.

[0045] The deposition of the nanospheres onto the tumor tissue isimproved by optimizing particle size to ensure entrainment of thenanospheres within the target tissue and by modifying the surfaceproperties of the nanospheres to enhance their affinity for a particularresidue expressed on a cell surface or enhance their affinity for a cellsurface protein or receptor to maximize interaction between thenanospheres and the tumor tissue, as shown in FIG. 3. With respect tothe interaction between the nanospheres and the target surface, variouschemical groups and bioadhesive materials can be incorporated in thenanospheres structure, for improving interaction with the targetsurface. A cationic surface active agent creates positively chargednanospheres; an anionic surface active agent creates negatively chargednanospheres; a nonionic surface active creates neutral chargednanospheres; and a zwitterionic surface active agent creates variablecharged nanospheres.

[0046] In one embodiment, the nanospheres of the present invention arebioadhesive. Bioadhesive nanosphere can be created by incorporating abioadhesive material into the solid hydrophobic matrix of thenanospheres, by incorporating a bioadhesive material in the pH sensitivemicrosphere matrix, or by using a bioadhesive material in the nanospherematrix in conjunction with bioadhesive material in the microspherematrix.

[0047] The term “spheres” is intended to describe solid, substantiallyspherical particulates. It will be appreciated that the term “sphere”includes other particle shapes that can be formed in accordance with theteachings of the present invention.

[0048] The term “pH triggered release” is intended to mean that the rateof release is dependent of or regulated by the pH of the systemsurrounding media or environment.

[0049] The present invention also provides a method of treating cancertumors comprising administering an effective amount of microspheres thatare capable of enhancing the bioavailability of the pharmaceuticalactive ingredient encapsulated in solid hydrophobic nanospheres andrelease them over an extended period of time at a specified pH. The termextended period of time at a specified pH is intended to mean anextended release a selected pH suitable for treating a cellularproliferation disease characterized by the abnormal proliferation ofcells, such as cancer.

[0050] Frequent cancer tumor sites are the lung, colon, rectum, breast,prostate, testicles, bladder, uterus, liver, pancreas, ovary, head andneck and the like. Prevalent types of cancer include leukemia, centralnervous system cancers, brain cancer, melanoma, lymphoma, erythroleukemia, uterine cancer, bone cancer and head and neck cancer.

[0051] The pharmaceutical active ingredient encapsulated in thecontrolled release system of the present invention include, but are notlimited to, cytotoxic agents, chemotherapeutic agents, radionuclides,nucleic acids, hormones, proteins, secreted proteins, andbiopharmaceiticals including but not limited to antibodies orantibody-engineered therapeutic entities, ligands, receptors andmimetics thereof. Nucleic acids as used herein also includes gene baseddrugs or gene based treatment modalities, including the use of sense,and antisense nucleic acids, ribozymes, as well as chimericoligonucleotides constructs for gene correction. Antigens, includingprotein antigens, are agents for use in compositions of the presentinvention. Nucleic acids include DNA or RNA fragments, which encodefunctionally active or inactive or conditionally inactivatable proteins.

[0052] The invention further provides a method to effectively deliverand localize the therapeutic effect of chemotherapeutic agents to thetarget site or tumor tissue and maintain efficacious levels of theseagents at the target site for the duration of treatment, that reducesthe amount of adverse side effects such as vomiting, myelosuppression,cardiac toxicity, pulmonary fibrosis, hepatobiliary toxicity, andpericholangitis commonly associated with other current non-invasivetreatments.

[0053] A preferred embodiment of the present invention pertains to amethod of treating a tumor with the solid hydrophobic nanospheresencapsulated in a pH sensitive microsphere which contain a selectedanti-tumor substance and injecting the microspheres in a blood vesselsuitable for carrying the microspheres to the tumor.

[0054] The multi-component controlled release system of the presentinvention can comprise from about 1% to about 50% by weight hydrophobicmatrix, from about 1% to about 50% by weight pH sensitive matrix, fromabout 0% to about 10% by weight targeting materials, from about 0% toabout 20% by weight surface active agents, and from about 0.01% to about50% by pharmaceutical weight active ingredients. The hydrophobic matrixenhances bioavailability and sustains the diffusion rate of thepharmaceutical active ingredients, through the nanospheres and enablesthem to be released onto the target site over an extended period oftime. The microsphere has an average sphere size in the range from about0.1 micron to about 50 microns. The nanosphere has an average spheresize in the range from about 0.001 micron to about 1 micron and has amelting point in the range from about 30° C. to about 90° C. This lineardimension for any individual sphere represents the length of the longeststraight line joining two points on the surface of the sphere.

[0055] Additional components can be added to the carrier system or canbe incorporated into the nanospheres, the microspheres, or both the nanoand micro spheres matrices. The controlled release system of the presentinvention can readily include other pharmaceutical active agents,including but are not limited to: anti-oxidants; free radicalscavengers; anti-microbial agents; antibacterial agents; allergyinhibitors; anti-aging agents; antiseptics; analgesics;anti-inflammatory agents; healing agents; inflammation inhibitors;vasoconstrictors; vasodilators; wound healing promoters; peptides,polypeptides and proteins; anti-fungal; depilating agents;counterirritants; vitamins; amino acids and their derivatives; herbalextracts; flavoids; chelating agents; cell turnover enhancers; andnourishing agents. The additional components are usually present in anamount from about 1% to about 20% by weight of the spheres.

[0056] The controlled release compositions of the present invention canbe easily processed into articles of predetermined generic dimensions.Examples of articles include pharmaceutical doses, diagnosticsmaterials, implants including depots, imaging entities, medical devices,and the like.

[0057] I. Matrix Materials for Forming the Nanospheres

[0058] Considerations in the selection of the matrix material includegood barrier properties to the active ingredients, low toxicity andirritancy, stability, integrity, and high loading capacity for theactive agents of interest. Suitable wax materials for the compositionsand devices of the present invention are inert nontoxic materials with amelting point range between about 25° C. and about 150° C. andpenetration point of about 1 to about 10. Examples of wax materialsinclude natural waxes, synthetic waxes and mixtures thereof. Suitablewaxes also include natural, regenerated, or synthetic food approvedwaxes including animal waxes such as beeswax, vegetable waxes such ascarnauba, candelilla, sugar cane, rice bran, and bayberry wax, mineralwaxes such as petroleum waxes including paraffin and microcrystallinewax, and mixtures thereof.

[0059] Other wax materials that are known to those skilled in the artand suitable materials as described in “Industrial Waxes” Vol. I and II,by Bennett F.A.I.C., published by Chemical Publishing Company Inc., 1975and Martindale, “The Extra Pharmacopoeia”, The Pharmaceutical Press,28^(th) Edition pp. 1063-1072, 1982 can be used in the presentinvention.

[0060] Suitable fat materials and/or glyceride materials which can beused as matrix materials for forming the nanospheres of the presentinvention include, but are not limited to, the following classes oflipids: mono-, di and triglycerides, phospholipids, sphingolipids,cholesterol and steroid derivatives, terpenes and vitamins.

[0061] The fat material of the present invention can be a glycerideselected from monoglycerides, diglycerides, glyceryl monostearate,glyceryl tristearate and mixtures thereof. Other fat materials which canbe used are hydrogenated palm oil, hydrogenated palm kernel oil,hydrogenated peanut oil, hydrogenated rapeseed oil, hydrogenated ricebran oil, hydrogenated soybean oil, hydrogenated cottonseed oil,hydrogenated sunflower oil, partially hydrogenated soybean oil,partially hydrogenated cottonseed oil, and mixtures thereof.

[0062] Examples of solid fat materials, which can be used in the presentinvention, include solid hydrogenated castor and vegetable oils, hardfats, and mixtures thereof. Other fat materials which can be used,include triglycerides of food grade purity, which can be produced bysynthesis or by isolation from natural sources. Natural sources caninclude animal fat or vegetable oil, such as soy oil, as a source oflong chain triglycerides (LCT). Other triglycerides suitable for use inthe present invention are composed of a majority of medium length fattyacids (C10-C18), denoted medium chain triglycerides (MCT). The fattyacid moieties of such triglycerides can be unsaturated orpolyunsaturated and mixtures of triglycerides having various fatty acidmaterial.

[0063] Phospholipids which can be used include, but are not limited to,phosphatidic acids, phosphatidyl cholines with both saturated andunsaturated lipids, phosphatidyl ethanolamines, phosphatidylglycerols,phosphatidylserines, phosphatidylinositols, lysophosphatidylderivatives, cardiolipin, and beta-acyl-y-alkyl phospholipids. Examplesof phospholipids include, but are not limited to, phosphatidylcholinessuch as dioleoylphosphatidylcholine, dimyristoylphosphatidylcholine,dipentadecanoylphosphatidylcholine dilauroylphosphatidylcholine,dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine(DSPC), diarachidoylphosphatidylcholine (DAPC),dibehenoylphosphatidylcholine (DBPC), ditricosanoylphosphatidylcholine(DTPC), dilignoceroylphatidylcholine (DLPC); andphosphatidylethanolamines such as dioleoylphosphatidylethanolamine or1-hexadecyl-2-palmitoylglycerophosphoethanolamine. Syntheticphospholipids with asymmetric acyl chains (e.g., with one acyl chain of6 carbons and another acyl chain of 12 carbons) can also be used.

[0064] Steroids which can be used include as fat materials, but are notlimited to, cholesterol, cholesterol sulfate, cholesterol hemisuccinate,6-(5-cholesterol 3 beta-yloxy)hexyl6-amino-6-deoxy-1-thio-alpha-D-galactopyranoside, 6-(5-cholesten-3beta-tloxy)hexyl-6-amino-6-deoxyl-1-thio-alpha-D mannopyranoside andcholesteryl)4′-trimethyl 35 ammonio)butanoate. Additional lipidcompounds as fat material which can be used include tocopherol andderivatives, and oils and derivatized oils such as stearlyamine.

[0065] The fat material can be fatty acids and derivatives thereof whichcan include, but are not limited to, saturated and unsaturated fattyacids, odd and even number fatty acids, cis and trans isomers, and fattyacid derivatives including alcohols, esters, anhydrides, hydroxy fattyacids and prostaglandins. Saturated and unsaturated fatty acids that canbe used include, but are not limited to, molecules that have between 12carbon atoms and 22 carbon atoms in either linear or branched form.Examples of saturated fatty acids that can be used include, but are notlimited to, lauric, myristic, palmitic, and stearic acids. Examples ofunsaturated fatty acids that can be used include, but are not limitedto, lauric, physeteric, myristoleic, palmitoleic, petroselinic, andoleic acids. Examples of branched fatty acids that can be used include,but are not limited to, isolauric, isomyristic, isopalmitic, andisostearic acids and isoprenoids. Fatty acid derivatives include12-(((7′-diethylaminocoumarin-3yl)carbonyl)methylamino)-octadecanoicacid;N-[12-(((7′-diethylaminocoumarin-3-yl)carbonyl)methyl-amino)octadecanoyl]-2-aminopalmiticacid, N succinyl-dioleoylphosphatidylethanol amine andpalmitoyl-homocysteine; and/or combinations thereof. Mono, di andtriglycerides or derivatives thereof that can be used include, but arenot limited to, molecules that have fatty acids or mixtures of fattyacids between 6 and 24 carbon atoms, digalactosyldiglyceride,1,2-dioleoyl-sn-glycerol; 1,2-cdipalmitoyl-sn-3 succinylglycerol; and1,3-dipalmitoyl-2-succinylglycerol.

[0066] The nanospheres of the present invention can have a melting pointin the range from about 30° C. to about 90° C., preferably from about40° C. to about 90° C. The melting point of the spheres is typically afunction of the carrier matrix employed. Accordingly, preferred matrixmaterials have a melting point in the range of about 50° C. to about 80°C., preferably from about 60° C. to about 70° C. It should be understoodthat it is the melting point of the sphere rather than the melting pointof the carrier matrix that is important for use of the carrier system ofthe present invention.

[0067] II. Materials for Forming a Microsphere Matrix

[0068] The microsphere can be composed of purely pH sensitive materialsor be comprised of a mixture of pH sensitive materials, salt sensitive,water sensitive or bioadhesive materials.

[0069] pH Sensitive Materials

[0070] The pH-sensitive materials that are utilized to form themicrospheres of the present invention comprises any material orstructure that has the ability to maintain the integrity of themicrosphere at normal physiological pH, of about 7.4, until themicrospheres reach the pH found in or near cancerous tissue that is moreacidic than the surrounding normal tissues typically, between about 3.5and about 6.8. Suitable pH sensitive materials for targeting thecontrolled delivery system of the present invention to the tumor sitesare materials that have a threshold pH of about 6.8 or less,alternatively those with threshold pH of about 6.5 or less, andalternatively have threshold pH of about 6 or less.

[0071] The trigger pH is the threshold pH value or range of values atwhich either above or below the trigger pH the pH-sensitive materialdegrades, and/or dissolves. The microsphere can be formed to be stablein solutions and then as the pH increases above the trigger pH themicrospheres are activated to swell or dissolve. Likewise, microspherescan be formed to be stable in solutions and as the pH drops below thetrigger pH the microspheres are activated to swell or dissolve. Onceactivated, the active ingredients and the nanospheres are released.

[0072] In one embodiment a pH-sensitive trigger means is used such thatthe microsphere is capable of becoming more permeable to water and/orlosing physical strength following triggering by a solution of thedesired pH, either above or below the trigger pH. In another embodimenta pH-sensitive trigger means is used to hold together two nanosphereportions. The trigger means is capable of losing its adhesive quality orstrength, such as to degrade or dissolve, following triggering by asolution of the desired pH, either above or below the trigger pH. Thereduction in adhesion strength allows the hydrostatic pressure insidethe microsphere core to push apart the nanospheres portions heldtogether by the adhesive trigger means, thereby releasing the contentsof the nanospheres.

[0073] The pH-sensitive materials can be insoluble solids in acidic orbasic aqueous solutions, which dissolve, or degrade and dissolve, as thepH of the solution is neutral. The pH-sensitive materials can beinsoluble solids in acidic or basic aqueous solutions which dissolve, ordegrade and dissolve, as the pH of the solution rises above or dropsbelow a trigger pH value.

[0074] Exemplary pH-sensitive materials include copolymers of acrylatepolymers with amino substituents, acrylic acid esters, polyacrylamides,phthalate derivatives (i.e., compounds with covalently attachedphthalate moleties) such as acid phthalates of carbohydrates, amyloseacetate phthalate, cellulose acetate phthalate, other cellulose esterphthalates, cellulose ether phthalates, hydroxy propyl cellulosephthalate, hydroxypropyl ethylcellulose phthalate, hydroxypropyl methylcellulose phthalate, methyl cellulose phthalate, polyvinyl acetatephthalate, polyvinyl acetate hydrogen phthalate, sodium celluloseacetate phthalate, starch acid phthalate, styrene-maleic acid dibutylphthalate copolymer, styrene-maleic acid polyvinyl acetate phthalatecopolymer, styrene and maleic acid copolymers, formalized gelatin,gluten, shellac, salol, keratin, keratin sandarac-tolu, ammoniatedshellac, benzophenyl salicylate, cellulose acetate trimellitate,cellulose acetate blended with shellac, hydroxypropylmethyl celluloseacetate succinate, oxidized cellulose, polyacrylic acid derivatives suchas acrylic acid and acrylic ester copolymers, methacrylic acid andesters thereof, vinyl acetate and crotonic acid copolymers.

[0075] Examples of suitable pH sensitive polymers for use are theEudragit® polymers series from Rohm America Inc., a wholly-ownedsubsidiary of Degussa-Huls Corporation, headquartered in Piscataway,N.J., and an affiliate of Rohm GmbH of Darmstadt, Germany. EUDRAGIT® L30 D-55 and EUDRAGIT® L 100-55, pH dependent anionic polymer that issoluble at pH above 5.5 and insoluble blow pH 5. These polymers can beutilized for targeted drug delivery in the duodenum. EUDRAGIT® L 100 pHdependent anionic polymer that is soluble at pH above 6.0 for targeteddrug delivery in the jejunum. EUDRAGIT® S 100 pH dependent anionicpolymer that is soluble at pH above 7.0 for targeted drug delivery inthe ileum. EUDRAGIT® E 100 and EUDRAGIT® EPO, pH dependent cationicpolymer, soluble up to pH 5.0 and insoluble above pH 5.0 dependentcationic polymer, soluble up to pH 5.0 and insoluble above pH 5.0.Accordingly, suitable pH sensitive materials degrade or dissolve whensaid pH sensitive microsphere contacts a solution having a pH greaterthan about 5.

[0076] Additional pH-sensitive materials include poly functionalpolymers containing multiple groups that become ionized as the pH dropsbelow their pKa. A sufficient quantity of these ionizable groups must beincorporated in the polymer such that in aqueous solutions having a pHbelow the pKa of the ionizable groups, the polymer dissolves. Theseionizable groups can be incorporated into polymers as block copolymers,or can be pendent groups attached to a polymer backbone, or can be aportion of a material used to crosslink or connect polymer chains.Examples of such ionizable groups include polyphosphene, vinyl pyridine,vinyl aniline, polylysine, polyornithine, other proteins, and polymerswith substituents containing amino moieties.

[0077] pH-sensitive polymers which are relatively insoluble andimpermeable at the pH of the stomach, but which are more soluble andpermeable at the pH of the small intestine and colon includepolyacrylamides, phthalate derivatives such as acid phthalates ofcarbohydrates, amylose acetate phthalate, cellulose acetate phthalate,other cellulose ester phthalates, cellulose ether phthalates,hydroxypropylcellulose phthalate, hydroxypropylethylcellulose phthalate,hydroxypropylmethylcellulose phthalate, methylcellulose phthalate,polyvinyl acetate phthalate, polyvinyl acetate hydrogen phthalate,sodium cellulose acetate phthalate, starch acid phthalate,styrene-maleic acid dibutyl phthalate copolymer, styrene-maleic acidpolyvinylacetate phthalate copolymer, styrene and maleic acidcopolymers, polyacrylic acid derivatives such as acrylic acid andacrylic ester copolymers, polymethacrylic acid and esters thereof, polyacrylic methacrylic acid copolymers, shellac, and vinyl acetate andcrotonic acid copolymers.

[0078] Other pH-sensitive polymers include shellac; phthalatederivatives, particularly cellulose acetate phthalate, polyvinylacetatephthalate, and hydroxypropylmethylcellulose phthalate; polyacrylic acidderivatives, particularly polymethyl methacrylate blended with acrylicacid and acrylic ester copolymers; and vinyl acetate and crotonic acidcopolymers.

[0079] Anionic acrylic copolymers of methacrylic acid andmethylmethacrylate are also particularly useful coating materials fordelaying the release of compositions and devices until the compositionsand devices have moved to a position in the small intestine which isdistal to the duodenum. Copolymers of this type are available fromRohmPharma Corp, under the trade names Eudragit-L.R™ and Eudragit-S.R™,are anionic copolymers of methacrylic acid and methylmethacrylate. Theratio of free carboxyl groups to the esters is approximately 1:1 inEudragit-L.R™ and approximately 1:2 in Eudragit-S.RT™. Mixtures ofEudragit-L.R™ and Eudragit-S.R™ can also be used.

[0080] The pH-sensitive and salt sensitive materials can be blended withan inert water sensitive material. By inert is meant a material that isnot substantially affected by a change in pH or salt concentration inthe triggering range. By altering the proportion of a pH-sensitivematerial to inert material the time lag subsequent to triggering andprior to release can be tailored.

[0081] In an embodiment of the present invention, the micro sphere isformed of a pH sensitive material which is substantially insoluble andimpermeable at the pH of the stomach, and is more soluble and permeableat the pH of the small intestine. Preferably, the micro spheres aresubstantially insoluble and impermeable at pH less than about 5.0, andwater-soluble at pH greater than about 5.0. pH-sensitive polymers whichare relatively insoluble and impermeable at the pH of the stomach, butwhich are more soluble and permeable at the pH of the small intestineand colon include polyacrylamides, phthalate derivatives such as acidphthalates of carbohydrates, amylose acetate phthalate, celluloseacetate phthalate, other cellulose ester phthalates, cellulose etherphthalates, hydroxypropylcellulose phthalate,hydroxypropylethylcellulose phthalate, hydroxypropylmethylcellulosephthalate, methylcellulose phthalate, polyvinyl acetate phthalate,polyvinyl acetate hydrogen phthalate, sodium cellulose acetatephthalate, starch acid phthalate, styrene-maleic acid dibutyl phthalatecopolymer, styrene-maleic acid polyvinylacetate phthalate copolymer,styrene and maleic acid copolymers, polyacrylic acid derivatives such asacrylic acid and acrylic ester copolymers, polymethacrylic acid andesters thereof, poly acrylic methacrylic acid copolymers, shellac, andvinyl acetate and crotonic acid copolymers.

[0082] Suitable pH-sensitive polymers include shellac; phthalatederivatives, particularly cellulose acetate phthalate, polyvinylacetatephthalate, and hydroxypropylmethylcellulose phthalate; polyacrylic acidderivatives, particularly polymethyl methacrylate blended with acrylicacid and acrylic ester copolymers; vinyl acetate; crotonic acidcopolymers and Eudragit® polymers series from Rohm America Inc.

[0083] Water Sensitive Materials

[0084] Water-sensitive materials can be mixed with the pH or saltsensitive materials to form the microspheres of the present invention.Suitable water sensitive materials comprise polyvinyl pyrrolidone, watersoluble celluloses, polyvinyl alcohol, ethylene maleic anhydridecopolymer, methyl vinyl ether maleic anhydride copolymer, polyethyleneoxides, water soluble polyamide or polyester copolymers or homopolymersof acrylic acid such as polyacrylic acid, polystyrene acrylic acidcopolymers or starch derivatives, polyvinyl alcohol, polysaccharides,hydrocolloids, natural gums, proteins, and mixtures thereof. Examples ofsynthetic water sensitive polymers which are useful for the inventioninclude polyvinyl pyrrolidone, water soluble celluloses, polyvinylalcohol, ethylene maleic anhydride copolymer, methylvinyl ether maleicanhydride copolymer, acrylic acid copolymers, anionic polymers ofmethacrylic acid and methacrylate, cationic polymers withdimethyl-aminoethyl ammonium functional groups, polyethylene oxides,water soluble polyamide or polyester.

[0085] Examples of water soluble hydroxyalkyl and carboxyalkylcelluloses include hydroxyethyl and carboxymethyl cellulose,hydroxyethyl and carboxyethyl cellulose, hydroxymethyl and carboxymethylcellulose, hydroxypropyl carboxymethyl cellulose, hydroxypropyl methylcarboxyethyl cellulose, hydroxypropyl carboxypropyl cellulose,hydroxybutyl carboxymethyl cellulose, and the like. Also useful arealkali metal salts of these carboxyalkyl celluloses, particularly andpreferably the sodium and potassium derivatives.

[0086] The polyvinyl alcohol useful in the practice of the invention ispartially and fully hydrolyzed polyvinyl acetate, termed “polyvinylalcohol” with polyvinyl acetate as hydrolyzed to an extent, also termeddegree of hydrolysis, of from about 75% up to about 99%. Such materialsare prepared by means of any of Examples I-XIV of U.S. Pat. No.5,051,222 issued on Sep. 24, 1991, the specification for which isincorporated by reference herein.

[0087] Polyvinyl alcohol useful for practice of the present invention isMowiol® 3-83, having a molecular weight of about 14,000 Da and degree ofhydrolysis of about 83%, Mowiol® 3-98 and a fully hydrolyzed (98%)polyvinyl alcohol having a molecular weight of 16,000 Da commerciallyavailable from Gehring-Montgomery, Inc. of Warminister Pa. Othersuitable polyvinyl alcohols are: AIRVOL® 205, having a molecular weightof about 15,000-27,000 Da and degree of hydrolysis of about 88%, andVINEX® 1025, having molecular weight of 15,000-27,000 Da degree ofhydrolysis of about 99% and commercially available from Air Products &Chemicals, Inc. of Allentown, Pa.; ELVANOL® 51-05, having a molecularweight of about 22,000-26,000 Da and degree of hydrolysis of about 89%and commercially available from the Du Pont Company, Polymer ProductsDepartment, Wilmington, Del.; ALCOTEX® 78 having a degree of hydrolysisof about 76% to about 79%, ALCOTEX®D F88/4 having a degree of hydrolysisof about 86% to about 88% and commercially available from the HarlowChemical Co. Ltd. of Templefields, Harlow, Essex, England CM20 2BH; andGOHSENOL® GL-03 and GOHSENOL® KA-20 commercially available from NipponGohsei K.K., The Nippon Synthetic Chemical Industry Co., Ltd., of No.9-6, Nozaki Cho,Kita-Ku, Osaka, 530 Japan.

[0088] Suitable polysaccharides are polysaccharides of the non-sweet,coloidally-soluble types, such as natural gums, for example, gum arabic,starch derivates, dextrinized and hydrolyzed starches, and the like. Asuitable polysaccharide is a water dispersible, modified starchcommercially available as Capule®, N-Lok®, Hi-Cap™ 100 or Hi-Cap™ 200commercially available from the National Starch and Chemical Company ofBridgewater, N.J.; Pure-Cote™, commercially available from the GrainProcessing Corporation of Muscatine, Iowa. In the preferred embodimentthe natural gum is a gum arabic, commercially available from TIC GumsInc. Belcamp, Midland. Suitable hydrocolloids are xanthan, maltodextrin,galactomanan or tragacanth, preferably maltodextrins such as Maltrin™M100, and Maltrin™ M150, commercially available from the GrainProcessing Corporation of Muscatine, Iowa.

[0089] Bioadhesive Polymers

[0090] An orally ingested drug delivery system can adhere to either theepithelial surface or the mucus. For the delivery of bioactive activeingredients, it is advantageous to have the system adhere to theepithelium rather than solely to the mucous layer, although mucoadhesioncan also substantially improve bioavailability. For some types ofimaging purposes, adhesion to both the epithelium and mucus is desirablewhereas in pathological states, such as in the case of gastric ulcers orulcerative colitis, adhesion to cells below the mucous layer may occur.Duchene, et al., Drug Dev. Ind. Pharm. 14(2&3), 283-318 (1988), reviewsthe pharmaceutical and medical aspects of bioadhesive systems for drugdelivery. “Bioadhesion” is defined as the ability of a material toadhere to a biological tissue for an extended period of time.Bioadhesion is a solution to the problem of inadequate residence timeresulting from the stomach emptying and intestinal peristalsis, and fromdisplacement by ciliary movement. For sufficient bioadhesion to occur,an intimate contact is needed between the bioadhesive and the receptortissue, the bioadhesive must penetrate into the crevice of the tissuesurface and/or mucus, and mechanical, electrostatic, or chemical bondsform. Bioadhesive properties of the polymers are affected by both thenature of the polymer and by the nature of the surrounding media.Incorporating bioadhesive polymers in the microsphere of the presentinvention can be utilized to control or increase the absorption of thenanosphere through the mucosal lining, or to further delay transit ofthe nanosphere through the gastrointestinal passages. A bioadhesivepolymer as used in the disclosure is one that binds to mucosalepithelium under normal physiological conditions. Bioadhesion in thegastrointestinal tract proceeds in two stages: (1) viscoelasticdeformation at the point of contact of the synthetic material into themucus substrate, and (2) formation of bonds between the adhesivesynthetic material and the mucus or the epithelial cells. In general,adhesion of polymers to tissues can be achieved by (i) physical ormechanical bonds, (ii) primary or covalent chemical bonds, and/or (iii)secondary chemical bonds such as ionic. Physical or mechanical bonds canresult from deposition and inclusion of the bioadhesive material in thecrevices of the mucus or the folds of the mucosa. Secondary chemicalbonds, contributing to bioadhesive properties, can comprise dispersiveinteractions such as Van der Waals interactions and stronger specificinteractions, such as hydrogen bonds. Hydrophilic functional groupsprimarily responsible for forming hydrogen bonds include hydroxyl andthe carboxylic groups. Suitable bioadhesive polymers for use in thepresent invention include bioerodible hydrogels as described by H. S.Sawhney, C. P. Pathak and J. A. Hubell in Macromolecules. 1993,26:581-587, the teachings of which are incorporated herein,polyhyaluronic acids, casein, gelatin, glutin, polyanhydrides,polyacrylic acid, alginate, chitosan, poly(methyl methacrylates),poly(ethyl methacrylates), poly (butyl methacrylate), poly(isobutylmethacrylate), poly(hexl methacrylate), poly(isodecl methacrylate),poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methylacrylate), poly(isopropyl acrylate), poly(isobutyl acrylate), andpoly(octadecl acrylate) and poly(fumaric-co-sebacic)acid.

[0091] Polymers with enhanced bioadhesive properties can be providedwherein anhydride monomers or oligomers are incorporated into thepolymer. The oligomer excipients can be blended or incorporated into awide range of hydrophilic and hydrophobic polymers including proteins,polysaccharides and synthetic biocompatible polymers. Anhydrideoligomers can be combined with metal oxide particles to improvebioadhesion in addition to the use of organic additives alone. Organicdyes because of their electronic charge andhydrophobicity/hydrophilicity can either increase or decrease thebioadhesive properties of polymers when incorporated into the polymers.The incorporation of oligomer compounds into a wide range of differentpolymers which are not normally bioadhesive can be used to increase theadherence of the polymer to tissue surfaces such as mucosal membranes.

[0092] III. Targeting Mechanism

[0093] The nanospheres can be targeted specifically or non-specificallythrough the selection of the pH of the material forming the microsphere,the size of the nanosphere, and/or incorporation or attachment of aligand to the nanospheres. For example, biologically active molecules,or molecules affecting the charge, lipophilicity or hydrophilicity ofthe nanospheres, can be attached to the surface of the nanospheres.Additionally, molecules can be attached to the nanospheres whichminimize tissue adhesion, or which facilitate specific targeting of thenanosphere in vivo. Representative targeting molecules includeantibodies, ligands, lectins, and other molecules which are specificallybound by receptors on the surfaces of cells of a particular type.

[0094] The term “cell recognition component”, as used herein, refers toa molecule capable of recognizing a component on a surface of a targetedcell. Cell recognition components may include an antibody to a cellsurface antigen, a ligand for a cell surface receptor, such as cellsurface receptors involved in receptor-mediated endocytosis, peptidehormones, and the like.

[0095] In one embodiment of the present invention, the nanospheres aremodified with lectins attached to the nanosphere surface and targeted tomucosal epithelium of the small intestine and are absorbed into thesystemic circulation and lymphatic circulation. In an embodiment of thepresent invention, carbohydrates or lectins are used to target thenanospheres of the present invention to M cells and Peyer's Patch cellsof the small intestine. In another embodiment of the present inventionlectins which bind to fucosyl sugars are used to modify the nanospheres.Lectins are a heterogenous group of proteins or glycoproteins thatrecognize carbohydrate residues on cell surface glycoconjugates with ahigh degree of specificity. Examples of lectins that can be used tomodify the nanospheres of the present invention, include but are notlimited to, lectins specific for binding to fucosyl glycoconjugates,such as Ulex Europeas Agglutinin I (UEA); lectins specific for bindingto galactose/N-acetylgalactoseamine, such as Phaseolus vulgarishaemagglutinin (PHA), tomato lectin (Lycopersicon esculentum) (TL),wheat germ agglutinin (WGA); lectins specific for binding to mannose,such as, Galanthus nivalis agglutinin (GNA); lectins specific formannose and/or glucose, such as, con A/concavalan A. (See e.g., Lehr etal., 1995, in Lectins Biomedical Perspectives, pp. 117-140, incorporatedby reference into this application). The targeting molecules can bederivatized if desired. See e.g., Chen et al., 1995, Proceed. Internat.Symp. Control. Rel. Bioact. Mater. 22 and Cohen WO 9503035, incorporatedby reference into this application.

[0096] In another embodiment of the invention, the nanospheres of thepresent invention can be modified with viral proteins or bacterialproteins that have an affinity for a particular residue expressed on acell surface or that have an affinity for a cell surface protein orreceptor. Examples of such proteins include, but are not limited to,cholera toxin B subunit, and bacterial adhesotopes.

[0097] In yet another embodiment of the present invention, thenanospheres of the present invention can be modified with monoclonalantibodies or fragments of antibodies which target the nanospheres to aparticular cell type. The nanospheres of the present invention can bemodified with ligands for specific mucosal cell surface receptors andproteins. As used herein, the term “ligand” refers to a ligand attachedto a nanosphere which adheres to the mucosa in the intestine or can beused to target the nanospheres to a specific cell type in the G-I tractor following absorption of the nanospheres onto the mucosa in theintestine. Suitable ligands can include ligands for specific cellsurface proteins and antibodies or antibody fragments immunoreactivewith specific surface molecules. Suitable ligands can also include lessspecific targeting ligands such as coatings of materials which arebioadhesive, for example alginate and polyacrylate.

[0098] IV. Active Ingredients

[0099] The pharmaceutical active ingredient encapsulated in thecontrolled release system of the present invention include, but are notlimited to, cytotoxic agents, chemotherapeutic agents, radionuclides,gene based drugs or gene based treatment modalities, including the useof sense, antisense nucleotide sequences, antigens, antibodies,ribozymes, as well as chimeric oligonucleotides constructs for genecorrection. These actives may also include DNA or RNA fragments, whichcode functionally active or inactive or conditionally inactivatableproteins. Examples of chemotherapeutic agents include inhibitors ofpurine synthesis (e.g., pentostatin, 6-mercaptopurine, 6thioguanine,methotrexate) or pyrimidine synthesis (e.g. Pala, azarbine), theconversion of ribonucleotides to deoxyribonucleotides (e.g.hydroxyurea), inhibitors of dTMP synthesis (5-fluorouracil), DNAdamaging agents (e.g. radiation, bleomycines, etoposide, teniposide,dactinomycine, daunorubicin, doxorubicin, mitoxantrone, alkylatingagents, mitomycin, cisplatin, procarbazine) as well as inhibitors ofmicrotubule function (e.g. vinca alkaloids and colchicine).

[0100] Although all taxanes are contemplated for formulation incompositions of the present invention an example suitable pharmaceuticalactive ingredient is, Paclitaxel, (also referred to as TAXOL®), firstidentified in 1971 by Wani and collaborators (Wani MC et al., J. Am.Chem. Soc., 93: pp. 2325-2327, 1971) following a screening program ofplant extracts of the National Cancer Institute. This complex diterpeneshows cytotoxic activity against several types of tumors and ispresently used in the treatment of some cancers such as ovarian andbreast cancers. Clinical studies suggest that Paclitaxel couldeventually be used in the treatment of over 70% of human cancers.Paclitaxel differs from other cytotoxic drugs by its unique mechanism ofaction. It interferes with cell division by manipulating the molecularregulation of the cell cycle. Paclitaxel binds to tubulin, the majorstructural component of microtubules that are present in all eukaryoticcells. Unlike other antimitotic agents such as vinca alkaloids andcolcichine, which inhibit the polymerization of tubulin, paclitaxelpromotes this assembly of tubulin and stabilizes the resultingmicrotubules. This event leads to the interruption of cell division, andultimately to cell death. Various derivatives of paclitaxel may be usedin accordance with the invention, such as taxotere or other relatedtaxanes. Cisplatin, another of the cytotoxic chemical compounds, whichmay be used in accordance with the invention, also is known ascis-Diamminedichloroplatinum. Well known analogues of cisplatin such ascarboplatin and iproplatin (also known asCHIP[cis-dichloro-trans-dihydroxo-bis[isopropylamine]platinum IV) canalso be used in the present invention. It will be appreciated those ofordinary skill in the art would be familiar with other specificcytotoxic agents that could be used in the present invention.

[0101] Other pharmaceutical compounds that are particularly well-suitedfor encapsulation according to the present invention, include:Tamoxifen, Dacarbazine, Ifosfamide, Streptozocin, Thiotepa, Nandrolonedecanoate, Fentanyl citrate, Testosterone, Albendazole, Esmolol,Mytomycin, Bleomycin sulfate, Dactinomycin, Amikacin sulfate,Gentamicin, Netilmicin, Streptomycin, Tobramycin, Doxorubicin,Epirubicin, Idarubicin, Valrubicin, Bacitracin, Colistimethate,Oxybutinin, Antithrombin III Human, Heparin, Lepirudin, Adenosinephosphate, Amphotericin B, Enalaprilat, Cladribine, Cytarabine,Fludarabine phosphate, Gemcitabine, Pentostatin, Docetaxel, Paclitaxel,Vinblastine, Vincristihe, Vinorelbine, Batimastat, Rituximab,Trastazumab, Abciximab, Eptifibatide, Tirofiban, Droperidol,Aurothioglucose, Capreomycin disulfide, Acyclovir, Cidofovir,Pentafuside, Saquinavir, Ganciclovir, Cromolyn, Aldesleukin, Denileukin,Edrophonium, Infliximab, Doxapram, SN-38 (Irinotecan), Topotecan, Hemin,Daunorubicin, Teniposide, Trimetrexate, Octreotride, Ganirelix acetate,Histrelin acetate, Somatropin, Epoetin, Filgrastim, Oprelvekin,Leuprolide, Basiliximab, Daclizumab, Glatiramer acetate, Interferons,Muromonab-CD3, Clyclosporin A, Milrinone lactate, Buprenorphine,Nalbuphine, Urofollitropin, Desmopressin, Carboplatin, Cisplatin,Mitoxantrone, Estradiol, Hydroxyprogesterone, L-Thyroxine, Etanercept,Neostigmine, Epoprostenol, Methoxamine, Versed, Bupivacaine, Heparin,Insulin, Antisense compounds, Ibuprofen, Fluorouracil, Mechlor,Fluorouridine, Tiazofurin Ketoprofen, Thanive, Etoposide, Docetaxel,Alendronate, Etidronate, Zoledronate, Ibandronate, Risedronate, andPamidronate. These compounds represent the following classes of drug:Alkylating agent, Anabolic steroid, Analgesic, Androgen, Anthelmintic,Antiadrenergic, Antibiotic, Antibiotic, aminoglycoside, Antibiotic,antineoplastic, Antibiotic, polypeptide, Anticholinergic, Anticoagulant,Anticonvulsant, Antifungal, Antihypertensive, Antimetabolite,Antimitotic, Antineoplastic, Antiplatelet, Antipsychotic, Anesthetic,Antirheumatic, Antituberculosal, Antiviral, Antiviral (HIV), Asthmaanti-inflammatory, Biological response modifier, Cholinergic musclestimulant, CNS stimulant, DNA topoisomerase inhibitor, Enzyme inhibitor,Epipodophyllotoxin, Folate antagonist, Gastric antisecretory, Genetherapy agents, Gonadotropin-releasing, Growth hormone, Hematopoietic,Hormone, Immunologic agent, Immunosuppressant, Inotropic agent, Localanesthetic, Narcotic agonist/antagonist, Ovulation stimulant, Pituitaryhormone, Platinum complex, Sex hormone, Thyroid hormone, TNF inhibitor(arthritis), Urinary cholinergic, Vasodilator, and Vasopressor. Othersuitable active agents are described in U.S. Pat. No. 6,656,955 herebyincorporated by reference into this application. The present inventionis very well suited for the incorporation of functional excipients, suchas gum benzoin or essential oils that improve absorption ofpoorly-absorbed drugs, in some cases by inhibiting drug efflux proteins.As discussed in more detail elsewhere herein, there are a number ofsites within, and at the surface of the particles, where actives,excipients, and functional excipients can be localized within thecontext of this invention.

[0102] V. Processing Method

[0103] Va. Nanospheres

[0104] The encapsulated active agent in the nanospheres of the presentinvention can be prepared by the steps of (1) heating hydrophobicmaterials to a temperature above the melting point to form a melt, (2)dissolving or dispersing the active agent in the melt, (3) emulsifyingthe melt in the aqueous phase; and (4) cooling the dispersion to ambienttemperature to form a fine suspension.

[0105] The active ingredients can be incorporated into hydrophobic solidnanospheres, the pH sensitive microsphere, or in both the nano and microspheres.

[0106] Vb. Microspheres

[0107] The controlled release system of the present invention can beprepared by the steps of (a) incorporating the selected active agentsinto the hydrophobic interior of the nanospheres, (b) forming an aqueousmixture comprising one or more active agents, the nanospheres, and a pHsensitive material, and (c) spray drying the mixture of the presentinvention to form a dry powder composition. Accordingly, the nanospherescan be encapsulated into the microsphere structure. One or more of theactive agents, which can be the same or different than the active agentsincorporated in the nanosphere, can be incorporated into the microspherestructure.

[0108] A process for producing the multi component controlled releasesystem includes the following steps:

[0109] (i) heating a hydrophobic material to a temperature above themelting point to form a melt;

[0110] (ii) dissolving or dispersing the selected first active agentinto the melt;

[0111] (iii) dissolving or dispersing a second active agent, and the pHsensitive materials, in the aqueous phase and heating it to above themelting temperature of the hydrophobic material;

[0112] (iv) mixing the hot melt with the aqueous phase to form adispersion;

[0113] (v) high shear homogenization of the dispersion at a temperatureabove the melting temperature until a homogeneous fine dispersion isobtained having a sphere size of from about 1 microns to about 2microns;

[0114] (vi) cooling the dispersion to ambient temperature; and

[0115] (vii) spray drying the emulsified mixed suspension to form a drypowder composition.

[0116] Homogenization can be accomplished in any suitable fashion with avariety of mixers known in the art such as simple paddle or ribbonmixers although other mixers, such as ribbon or plow blenders, drumagglomerators, and high shear mixers may be used. Suitable equipment forthis process include a model Rannie 100 lab homogenizer available fromAPV Gaulin Inc. Everett, Mass., a rotor stator high shear mixeravailable from Silverson Machines, of East Long Meadow, Mass., or ScottProcessing Equipment Corp. of Sparta, N.J., and other high sear mixers.

[0117] The suspension is spray dried to remove the excess water. Spraydrying is well known in the art and been used commercially in manyapplications, including foods where the core material is a flavoring oiland cosmetics where the core material is a fragrance oil. Cf. Balassa,“Microencapsulation in the Food Industry”, CRC Critical Review Journalin Food Technology, July 1971, pp 245-265; Barreto, “Spray DriedPerfumes for Specialties, Soap and Chemical Specialties”, December 1966;Maleeny, Spray Dried Perfumes, Soap and San Chem, January 1958, pp. 135et seq.; Flinn and Nack, “Advances in Microencapsulation Techniques”,Batelle Technical Review, Vo. 16, No. 2, pp. 2-8 (1967); U.S. Pat. Nos.5,525,367; and 5,417,153 which are incorporated herein as references.

[0118] The use of pH activated microspheres which provide varying ratesof diffusion are contemplated. For example, the active ingredientsencapsulated in the pH activated microspheres may diffuse at any of therates of the following:

[0119] at steady-state or zero-order release rate in which there is asubstantially continuous release per unit of time;

[0120] a first-order release rate in which the rate of release declinestowards zero with time; and

[0121] a delayed release in which the initial rate is slow, but thenincreases with time.

[0122] Nanospheres formed of a hydrophobic material provide a controlledrelease system in order to release the active agent over an extendedperiod of time by molecular diffusion. Active agents in the hydrophobicmatrix of the nanospheres can be released by transient diffusion. Thetheoretical early and late time approximation of the release rate of theactive ingredients dissolved in the hydrophobic matrix of thenanospheres can be calculated from the following equations:

[0123] Early time approximation

(m_(t)/m_(sec))<0.4 $\begin{matrix}{\frac{M_{t}}{M_{\infty}} = {{4\left( \frac{D_{p}t}{\Pi \quad r^{2}} \right)^{1/2}} - \frac{D_{p}t}{r^{2}}}} & (1) \\{\frac{{M_{t}}/M_{\infty}}{t} = {{2\left( \frac{D_{p}}{\Pi \quad r^{2}t} \right)^{1/2}} - \frac{D_{p}}{r^{2}}}} & (2)\end{matrix}$

[0124] Late time approximation

(m_(t)/m_(∞))>0.6 $\begin{matrix}{\frac{M_{t}}{M_{\infty}} = {1 - {\frac{4}{(2.405)^{2}}{\exp \left( \frac{{- (2.405)^{2}}D_{p}t}{r^{2}} \right)}}}} & (3) \\{\frac{{M_{t}}/M_{\infty}}{t} = {1 - {\frac{4D_{p}}{r^{2}}{\exp \left( \frac{{- (2.405)^{2}}D_{p}t}{r^{2}} \right)}}}} & (4)\end{matrix}$

[0125] wherein:

[0126] r is the radius of the cylinder,

[0127] m_(∞) is the amount of active agent released from the controlledrelease system after infinite time;

[0128] m_(t) is the amount of active agent released from the controlledrelease system after time t; and

[0129] D_(p) is the diffusion coefficient of the active agent in thematrix.

[0130] The release rate for releasing the active agents from thehydrophobic nanospheres is typically slower than the release rate forreleasing active agent from the pH sensitive matrix. The active agentscan be selected to be incorporated into either the hydrophobicnanospheres or the pH sensitive matrix depending on the desired time forrelease of the active agents. For example, a predetermined first activeagent can be incorporated in the pH or salt sensitive matrix to bereleased first and a predetermined second active agent can beincorporated in the hydrophobic nanospheres for release over an extendedperiod of time during or after the first agent has been released. Forexample, the pH sensitive matrix formed in accordance with the presentinvention can release the first active agent at a predetermined pH toprovide a “burst” with continued release of the first active agent andnanospheres formed in accordance with the present invention can releasethe active agent depending on the release rate from an initial time suchas a day or within few days, up to a period of few weeks.

[0131] In the preferred embodiment, the active agent is present at alevel from about 0.01% to about 60%, preferably from about 1% to about50% by weight of the microsphere. In the preferred embodiment, thenanospheres are generally present in the pH sensitive matrix at a levelfrom about 1% to about 80%, preferably from about 1% to about 60% byweight of the matrix material with the balance being the active agents,and the pH sensitive materials. In the preferred embodiment, the pHsensitive matrix is generally present at a level from about 1% to about80%, preferably from about 1% to about 60% by weight of the matrixmaterial with the balance being the active agents, and the hydrophobicmaterials.

[0132] The subject methods may be used to treat a wide variety of hosts,including mammalian hosts, such as domestic animals, e.g. pets andlivestock, rare or exotic animals, and humans. Cellular proliferativediseases amenable to treatment with the subject formulations arediseases characterized by the abnormal proliferation of cells. Diseasescharacterized by the abnormal proliferation of cells include neoplasia,psoriasis, hyperplasia and the like.

[0133] Neoplastic diseases amenable to treatment according to thesubject methods include neoplastic dieases characterized by thedevelopment of solid tumors or lesions, including solid malignant tumorsof the lung, breast, colon, rectum, ovaries, stomach, pancreas, uterus,testicles, brain, liver, head and neck.

[0134] Particular neoplastic cellular proliferative diseases that may betreated with the subject methods include carcinomas, sarcomas andmelanomas, such as basal cell carcinoma, squamous cell carcinoma,melanoma, soft tissue sarcoma, solar keratoses, Kaposi's sarcoma,cutaneous malignant lymphoma, Bowen's disease, Wilm's tumor, hepatomas,colorectal cancer, brain tumors, mycosis fungoides, Hodgkins lymphoma,polycythemia ver, lymphomas, oat cell sarcoma, superficial and invasivebladder tumors, ovarian cancer, etc.

[0135] The compounds can be administered orally, rectally, parenterally,or by injection, alone or in combination with other therapeutic agentsincluding antibiotics, steroids, etc., to a mammal in need of treatment.Oral dosage forms include tablets, capsules, dragees, and similarshaped, compressed pharmaceutical forms. Isotonic saline solutionscontaining 20-100 milligrams/milliliter can be used for parenteraladministration which includes intramuscular, intrathecal, intravenousand intra-arterial routes of administration. Rectal administration canbe effected through the use of suppositories formulated fromconventional carriers such as cocoa butter.

[0136] Dosage regimens must be titrated to the particular indication,the age, weight, and general physical condition of the patient, and theresponse desired but generally doses will be from about 1 to about 1000milligrams/day as needed in single or multiple daily administration.

[0137] The compositions preferably are formulated in unit dosage form,meaning physically discrete units suitable as a unitary dosage, or apredetermined fraction of a unitary dose to be administered in a singleor multiple dosage regimen to human subjects and other mammals, eachunit containing a predetermined quantity of active material calculatedto produce the desired therapeutic effect in association with a suitablepharmaceutical excipient.

[0138] Pharmaceutical compositions thus comprise one or more compoundsof the present invention associated with at least one pharmaceuticallyacceptable carrier, diluent or excipient. In preparing suchcompositions, the active ingredients are usually mixed with or dilutedby an excipient or enclosed within such a carrier which can be in theform of a capsule or sachet. When the excipient serves as a diluent, itmay be a solid, semi-solid, or liquid material which acts as a vehicle,carrier, or medium for the active ingredient. Thus the compositions canbe in the form of tablets, pills, powders, elixirs, suspensions,emulsions, solutions, syrups, soft and hard gelatin capsules,suppositories, sterile injectable solutions and sterile packagedpowders. Examples of suitable excipients include lactose, dextrose,sucrose, sorbitol, mannitol, starch, gum acacia, calcium silicate,microcrystalline cellulose, polyvinylpyrrolidinone, cellulose, water,syrup, and methyl cellulose, the formulations can additionally includelubricating agents such as talc, magnesium stearate and mineral oil,wetting agents, emulsifying and suspending agents, preserving agentssuch as methyl- and propylhydroxybenzoates, sweetening agents orflavoring agents.

[0139] The carrier system of the present invention can be incorporatedin pharmaceutical and health care products.

[0140] The invention can be further illustrated by the followingexamples thereof, although it will be understood that these examples areincluded merely for purposes of illustration and are not intended tolimit the scope of the invention unless otherwise specificallyindicated. All percentages, ratios, and parts herein, in theSpecification, Examples, and claims, are by weight and areapproximations unless otherwise stated.

Preparation of a pH Sensitive Drug Delivery Systems EXAMPLE 1

[0141] The following procedure is used for the preparation of multicomponent controlled release system with the chemotherapeutic drugpaclitaxel (taxol), a high molecular weight, lipophilic deterpenoidisolated from the western yew, as the active agent encapsulated in thesolid hydrophobic nanosphere matrix. The nanosphere hydrophobic matrixis candelilla wax, commercially available from Strahl & Pitsch Inc. ofWest Babylon, N.Y. The microsphere pH sensitive matrix is a pH dependentanionic polymer stable at pH 7.4 and solubilizing at pH 6 and lower.

[0142] 40 grams of candelilla wax is placed in an oven at 80° C. andallowed to melt. 500 grams of deionized water are placed into Igallonvessel, fitted with an all-purpose silicon rubber heater (Cole-PalmerInstrument Company). 50 grams of the pH sensitive polymer were added tothe water and the aqueous solution is heated to 90° C. while mixing itwith a propeller mixer. The candelilla wax is removed from the oven. 10grams of paclitaxel are dispersed into the melt by hand with a glassrod. The drug/wax mixture is poured into the aqueous solution and thedispersion is homogenized at 25,000 psi using a Rannie 100 labhomogenizer available from APV Gaulin Inc. The dispersion is cooled toambient temperature by passing it through a tube-in-tube heat exchanger(Model 00413, Exergy Inc. Hanson Mass.) to form a suspension. Theresulting suspension is spray dried with a Bowen Lab Model Drier (atSpray-Tek of Middlesex, N.J.) utilizing 250 c.f.m of air with an inlettemperature of 380° F., and outlet temperature of 225° F. and a wheelspeed of 45,000 r.p.m to produce a free flowing, dry powder, consistingof 10% paclitaxel.

EXAMPLE 2

[0143] The following procedure is used for the preparation of multicomponent controlled release system with the chemotherapeutic drugdoxorubicin (hydroxydaunomycin hydrochloride) (commercially availablefrom Sigma) as the drug encapsulated in the solid hydrophobic nanospherematrix. Doxorubicin (hydroxydaunomycin hydrochloride) is commerciallyavailable as the hydrochloride salt. It is an antineoplastic antibioticbut it is too cytotoxic to be used as an anti-infective agent. The exactmechanism of its anticancer activity is not well understood but someevidence suggests that the drug forms a complex with DNA which inhibitsboth DNA synthesis and DNA-dependent RNA synthesis by the resultingtemplate disordering. Cells that are the most sensitive to doxorubicinare from rapidly proliferating tissues such as those of normal bonemarrow, gastrointestinal mucosa, and hair follicles (Budavari, et al.,1989). Doxorubicin is administered intravenously and commonly used inthe treatment of solid tumors including bladder carcinoma, breastcarcinoma, ovarian carcinoma, gastric carcinoma, malignant lymphomas,and acute lymphoblastic and myeloblastic leukemias. Doxorubicin israpidly metabolized in a first pass effect through the liver by analdo-keto reductase enzyme which forms doxorubicinol, the metabolitewith the major antineoplastic activity. A common adult dose ofdoxorubicin would be a 60 to 75 mg/m² (skin area), intravenous injectiononce every 21 days, but other schedules require smaller injections(20-30 mg/m²) either once weekly or for 3 to 4 successive days every fewweeks (Trissel, L. A., Handbook on Injectable Drugs, (8^(th) ed.),American Society of Hospital Pharmacists, Inc., 1994). The nanospherehydrophobic matrix is candelilla wax, commercially available from Strahl& Pitsch Inc. of West Babylon, N.Y. The microsphere pH sensitive matrixis a pH dependent anionic polymer stable at pH 7.4 and solubilizing atpH 6 and lower.

[0144] 40 grams of candelilla wax is placed in an oven at 80° C. andallowed to melt. 500 grams of deionized water are placed into 1 gallonvessel, fitted with an all-purpose silicon rubber heater (Cole-PalmerInstrument Company). 50 grams of the pH sensitive polymer were added tothe water and the aqueous solution is heated to 90° C. while mixing itwith a propeller mixer. The candelilla wax is removed from the oven. 10grams of doxorubicin are dispersed into the melt by hand with a glassrod. The drug/wax mixture is poured into the aqueous solution and thedispersion is homogenized at 25,000 psi using a Rannie 100 labhomogenizer available from APV Gaulin Inc. The dispersion is cooled toambient temperature by passing it through a tube-in-tube heat exchanger(Model 00413, Exergy Inc. Hanson Mass.) to form a suspension. Theresulting suspension is spray dried with a Bowen Lab Model Drier (atSpray-Tek of Middlesex, N.J.) utilizing 250 c.f.m of air with an inlettemperature of 380° F., and outlet temperature of 225° F. and a wheelspeed of 45,000 r.p.m to produce a free flowing, dry powder, consistingof 10% doxorubicin.

EXAMPLE 3

[0145] The following procedure is used for the preparation of multicomponent controlled release system with the chemotherapeutic drugfluorodeoxyuridine (FUDR) (commercoially available Sigma) as the activeagent encapsulated in the hydrophobic nanosphere matrix. The nanospherehydrophobic matrix is beeswax wax, commercially available from Strahl &Pitsch Inc. of West Babylon, New-York. The microsphere pH sensitivematrix is a pH dependent anionic polymer stable at pH 7.4 andsolubilizing at pH 6 and lower. 40 grams of beeswax wax is placed in anoven at 80° C. and allowed to melt. 500 grams of deionized water areplaced into 1 gallon vessel, fitted with an all-purpose silicon rubberheater (Cole-Palmer Instrument Company). 50 grams of the pH sensitivepolymer were added to the water and the aqueous solution is heated to90° C. while mixing it with a propeller mixer. The beeswax is removedfrom the oven, 10 grams of fluorodeoxyuridine are mixed into the melt byhand with a glass rod. The drug/wax mixture is poured into the aqueoussolution and the dispersion is homogenized at 25,000 psi using a Rannie100 lab homogenizer available from APV Gaulin Inc. The dispersion iscooled to ambient temperature by passing it through a tube-in-tube heatexchanger (Model 00413, Exergy Inc. Hanson Mass.) to form a suspension.The resulting suspension is spray dried with a Bowen Lab Model Drier (atSpray-Tek of Middlesex, N.J.) utilizing 250 c.f.m of air with an inlettemperature of 380° F., and outlet temperature of 225° F. and a wheelspeed of 45,000 r.p.m to produce a free flowing, dry powder, consistingof 10% fluorodeoxyuridine.

[0146] It is to be understood that the above-described embodiments areillustrative of only a few of the many possible specific embodimentswhich can represent applications of the principles of the invention.Numerous and varied other arrangements can be readily devised inaccordance with these principles by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A controlled release composition comprising: aplurality of solid nanospheres encapsulated in a microsphere formed of apH sensitive or salt sensitive matrix material, and a first active agentincorporated into at least one of: the nanospheres or the microsphere;wherein said first active agent is selected from the group consisting ofa cytotoxic agent, a chemotherapeutic agent, an anti-oncology agent, aradionuclide, a nucleic acid, a protein, and a biopharmaceutical.
 2. Thecomposition of claim 1 wherein said first pharmaceutical active agent isincorporated into the nanospheres and a second pharmaceutical activeagent is incorporated into the microsphere wherein said second activeagent is selectively released upon contact with an aqueous solutionhaving a predetermined pH or predetermined salt concentration.
 3. Thecomposition according to claim 1 wherein said microsphere degrades ordissolves in an aqueous solution having a pH within the range of about3.5 to about 6.8.
 4. The composition according to claim 1 wherein themicrosphere degrades or dissolves in an aqueous solution at a pH lowerthan about 6.8.
 5. The composition according to claim 1 wherein themicrosphere degrades or dissolves in an aqueous solution at pH lowerthan about 6.5.
 6. The composition according to claim 1 wherein themicrosphere degrades or dissolves in an aqueous solution at a pH lowerthan about
 6. 7. The composition of claim 1 wherein said pH sensitivematrix is relatively insoluble and impermeable at a normal physiologicalpH of about 7.4, and is more soluble and permeable at an ambient pH ator near cancerous tissue at a pH between about 3.5 and about 6.8.
 8. Thecomposition of claim 1 wherein said pH sensitive matrix material isselected from the group consisting of: acrylate polymers with aminosubstituents, acrylic acid esters, polyacrylamides, phthalatederivatives and mixtures thereof.
 9. The composition of claim 1 whereinsaid pH sensitive matrix material is selected from the group consistingof: acid phthalate of carbohydrate, amylose acetate phthalate, celluloseacetate phthalate, cellulose ester phthalate, cellulose ether phthalate,hydroxy propyl cellulose phthalate, hydroxypropyl ethylcellulosephthalate, hydroxypropyl methyl cellulose phthalate, methyl cellulosephthalate, polyvinyl acetate phthalate, polyvinyl acetate hydrogenphthalate, sodium cellulose acetate phthalate, starch acid phthalate,styrene-maleic acid dibutyl phthalate copolymer, styrene-maleic acidpolyvinyl acetate phthalate copolymer, styrene and maleic acidcopolymer, gelatin, gluten, shellac, salol, keratin, keratinsandarac-tolu, ammoniated shellac, benzophenyl salicylate, celluloseacetate trimellitate, cellulose acetate blended with shellac,hydroxypropylmethyl cellulose acetate succinate, oxidized cellulose,polyacrylic acid derivative, acrylic acid and acrylic ester copolymers,methacrylic acid, methacrylic acid ester, vinyl acetate, crotonic acidcopolymer and mixtures thereof.
 10. The composition according to claim 1wherein a first portion of said plurality of nanospheres are adhered toa second portion of said plurality of nanospheres with a pH sensitivematrix material.
 11. The composition according to claim 1 furthercomprising a moisture sensitive material mixed with said pH sensitive orsalt sensitive material of said microsphere.
 12. The compositionaccording to claim 11 wherein said moisture sensitive material isselected from the group consisting of polyvinyl pyrrolidone, watersoluble cellulose, polyvinyl alcohol, ethylene maleic anhydridecopolymer, methyl vinyl ether maleic anhydride copolymer, polyethyleneoxides, polyamide, polyester, copolymers or homopolymers of acrylicacid, polyacrylic acid, polystyrene acrylic acid copolymer, starchderivatives, polyvinyl alcohol, acrylic acid copolymer, anionic polymerof methacrylic acid and methacrylate, cationic polymer havingdimethyl-aminoethyl ammonium functional groups, hydroxyethyl cellulose,carboxymethyl cellulose, hydroxymethyl cellulose, carboxymethylcellulose, hydroxypropyl carboxymethyl cellulose, hydroxypropyl methylcarboxyethyl cellulose, hydroxypropyl carboxypropyl cellulose,hydroxybutyl carboxymethyl cellulose, polysaccharide, hydrocolloid,natural gum, protein, and mixtures thereof.
 13. The composition of claim1 wherein said solid nanospheres are formed of a wax material having amelting point in the range of between about 25° C. and about 150° C. 14.The composition of claim 13 wherein said wax material has a penetrationpoint of about 1 to about
 10. 15. The composition of claim 13 whereinsaid wax material is selected from the group consisting of: natural wax,synthetic wax, regenerated wax, vegetable wax, animal wax, mineral wax,petroleum wax, microcrystalline wax and mixtures thereof.
 16. Thecomposition of claim 13 wherein said wax comprises one or more ofcarnauba wax, candelilla wax and beeswax.
 17. The composition of claim 1wherein said solid nanospheres are formed of a fat material selectedfrom the group consisting of: hydrogenated castor oil, hydrogenatedvegetable oil, hard fat, glyceride, fatty acids, fatty acid derivative,lipid, steroid and mixtures thereof.
 18. The composition of claim 17wherein said glyceride is selected from the group consisting of:triglyceride, monoglyceride, diglyceride, glyceryl monostearate,glycerol tristearate and mixtures thereof.
 19. The composition of claim17 wherein said fatty acid derivative is selected from the groupconsisting of: alcohol, ester, anhydride, hydroxy fatty acid andprostaglandin.
 20. The composition of claim 17 wherein said fat materialis selected from the group consisting of: lauric acid, physeteric acid,myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid,isolauric acid, isomyristic acid, isopalmitic acid, isostearic acid,isoprenoid,12-(((7′-diethylaminocoumarin-3yl)carbonyl)methylamino)-octadecanoicacid,N-[12-(((7′-diethylaminocoumarin-3-yl)carbonyl)methyl-amino)octadecanoyl]-2-aminopalmiticacid, N succinyl-dioleoylphosphatidylethanol amine,palmitoyl-homocysteine, digalactosyldiglyceride,1,2-dioleoyl-sn-glycerol; 1,2-cdipalmitoyl-sn-3 succinylglycerol;1,3-dipalmitoyl-2-succinylglycerol and mixtures thereof.
 21. Thecomposition of claim 17 wherein said fat material is selected from thegroup consisting of: phospholipid, sphingolipid, cholesterol, steroidderivative, terpene, tocopherol, stearlyamine, vitamin and mixturesthereof.
 22. The composition of claim 21 wherein said phospholipid isselected fom the group consisting essentially of phosphatidic acid,phosphatidyl choline, phosphatidyl ethanolamine, phosphatidylglycerol,phosphatidylserine, phosphatidylinositol, lysophosphatidyl derivative,cardiolipin, beta-acyl-y-alkyl phospholipid, phosphatidylcholines,dioleoylphosphatidylcholine, dimyristoylphosphatidylcholine,dipentadecanoylphosphatidylcholine, dilauroylphosphatidylcholine,dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine(DSPC), diarachidoylphosphatidylcholine (DAPC),dibehenoylphosphatidylcholine (DBPC), ditricosanoylphosphatidylcholine(DTPC), dilignoceroylphatidylcholine (DLPC), phosphatidylethanolamine,dioleoylphosphatidylethanolamine,1-hexadecyl-2-palmitoylglycerophosphoethanolamine, syntheticphospholipids and mixtures thereof.
 23. The composition of claim 21wherein said steroid derivative is selected from the group consistingof: cholesterol, cholesterol sulfate, cholesterol hemisuccinate,6-(5-cholesterol 3 beta-yloxy)hexyl6-amino-6-deoxy-1-thio-alpha-D-galactopyranoside, 6-(5-cholesten-3beta-tloxy)hexyl-6-amino-6-deoxyl-1-thio-alpha-D mannopyranoside,cholesteryl(4′-trimethyl 35 ammonio)butanoate and mixtures thereof. 24.The composition of claim 1, wherein said microsphere further comprises awater sensitive material selected from the group consisting of: naturaloligomer, synthetic oligomer, natural polymer, synthetic polymer andcopolymer, starch, starch derivative, oligosaccharide, polysaccharide,hydrocolloid, natural gum, protein, cellulose, cellulose derivative andmixtures thereof.
 25. The composition of claim 1 further comprising abioadhesive material incorporated into said solid nanosphere or saidmicrosphere or in both said nanosphere and said microsphere.
 26. Thecomposition of claim 25 wherein said bioadhesive material is abioadhesive polymer.
 27. The composition of claim 26 wherein saidbioadhesive polymer is selected from the group consisting ofpolyhyaluronic acids, casein, gelatin, glutin, polyanhydrides,polyacrylic acid, alginate, chitosan, poly(methyl methacrylates),poly(ethyl methacrylates), poly (butyl methacrylate), poly(isobutylmethacrylate), poly(hexl methacrylate), poly(isodecl methacrylate),poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methylacrylate), poly(isopropyl acrylate), poly(isobutyl acrylate),poly(octadecl acrylate) and poly(fumaric-co-sebacic)acid.
 28. Thecomposition of claim 1 wherein said nanosphere further comprises aligand.
 29. The composition of claim 1 wherein said nanosphere furthercomprises a targeting material selected from the group comprising lectinviral protein, bacterial protein, monoclonal antibody and antibodyfragment.
 30. The composition of claim 1 wherein said first active agentis selected from the group consisting of: cisplatin, camptothecin,vinblastine, paclitaxel, fluorouracil, docetaxel, fluorourideine,tiazofurin, doxorubicin, mechlorethamine, etoposide, mitomycin, andbleomycin.
 31. The composition of claim 1 wherein said nanospheresfurther comprise a cationic surface active agent, anionic surface activeagent, a nonionic surface active agent or a zwitterionic surface activeagent.
 32. The composition of claim 1 wherein said microsphere has asize within the range of about 20 to about 100 microns.
 33. Thecomposition according to claim 1 wherein each of said nanospheres has anaverage size within the range of about 0.01 to about 5 microns.
 34. Thecomposition according to claim 1 wherein said first active agent isincorporated in said microsphere and said nanospheres, wherein said pHor salt sensitive material upon contact with an aqueous solutionreleases said first active agent to provide a burst and said firstactive agent is released continuously thereafter for an extended periodof time.
 35. The composition according to claim 34 wherein the extendedperiod of time is within the range of about one day to about threeweeks.
 36. The composition according to claim 2 wherein upon contactwith said solution said second pharmaceutical agent is released toprovide a burst and said first pharmaceutical agent is releasedcontinuously thereafter for an extended period of time.
 37. Thecomposition according to claim 36 wherein the extended period of time iswithin the range of about one day to about three weeks.
 38. Apharmaceutical composition comprising a physiologically acceptablecarrier, and a controlled release composition comprising: a plurality ofsolid nanospheres encapsulated in a microsphere formed of a pH sensitiveor salt sensitive matrix material, and an effective amount of firstactive agent incorporated into at least one of: the nanospheres or themicrosphere; wherein said first active agent is selected from the groupconsisting of a cytotoxic agent, a chemotherapeutic agent, ananti-oncology agent, a radionuclide, a nucleic acid, a protein, and abiopharmaceutical.
 39. The pharmaceutical composition according to claim38 in a dosage form selected from the group consisting of powder,tablets, capsules and injectable compositions.
 40. An article comprisingthe composition of claim
 1. 41. A method for selectively delivering anactive substance to a preselected environment comprising aministering acontrolled release composition to an environment, said compositioncomprising: a plurality of solid nanospheres encapsulated in amicrosphere formed of a pH sensitive or salt sensitive matrix material,and a first active agent incorporated into at least one of: thenanospheres or the microsphere; wherein said first active agent isselected from the group consisting of a cytotoxic agent, achemotherapeutic agent, an anti-oncology agent, a radionuclide, anucleic acid, a protein, and a biopharmaceutical.
 42. The method ofclaim 41 wherein said environment is a mammal and said preselectedenvironment is a tumor.
 43. The method of claim 42 wherein said pHsensitive matrix material degrades or dissolves when the microspherecontacts a solution having a pH in the range of about 3.5 to about 6.8.44. The method of claim 43 wherein said pH sensitive material isselected from the group consisting of: acid phthalate of carbohydrate,amylose acetate phthalate, cellulose acetate phthalate, cellulose esterphthalate, cellulose ether phthalate, hydroxy propyl cellulosephthalate, hydroxypropyl ethylcellulose phthalate, hydroxypropyl methylcellulose phthalate, methyl cellulose phthalate, polyvinyl acetatephthalate, polyvinyl acetate hydrogen phthalate, sodium celluloseacetate phthalate, starch acid phthalate, styrene-maleic acid dibutylphthalate copolymer, styrene-maleic acid polyvinyl acetate phthalatecopolymer, styrene and maleic acid copolymer, gelatin, gluten, shellac,salol, keratin, keratin sandarac-tolu, ammoniated shellac, benzophenylsalicylate, cellulose acetate trimellitate, cellulose acetate blendedwith shellac, hydroxypropylmethyl cellulose acetate succinate, oxidizedcellulose, polyacrylic acid derivative, acrylic acid and acrylic estercopolymers, methacrylic acid, methacrylic acid ester, vinyl acetate,crotonic acid copolymer and mixtures thereof.
 45. The method of claim 42wherein a first portion of said plurality of nanospheres are adhered toa second portion of said plurality of nanospheres with a pH sensitive orsalt sensitive matrix material.
 46. The method of claim 42 furthercomprising a moisture sensitive material mixed with said pH sensitive orsalt sensitive material of said microsphere.
 47. The method of claim 42wherein said active agent is selected from the group consisting of:cisplatin, camptothecin, vinblastine, paclitaxel, fluorouracil,docetaxel, fluorourideine, tiazofurin, doxorubicin, mechlorethamine,etoposide, mitomycin, and bleomycin.
 48. The method of claim 42 furthercomprising a bioadhesive material incorporated into said solidnanosphere or said microsphere or in both said nanosphere and saidmicrosphere.
 49. The method of claim 48 wherein said bioadhesivematerial is a bioadhesive polymer.
 50. The method of claim 42 whereinsaid nanosphere further comprises a ligand.
 51. The method of claim 42wherein said nanosphere comprises a targeting material selected from thegroup consisting essentially of lectin, viral protein, bacterialprotein, monoclonal antibody and antibody fragment.
 52. A method fortreating a host suffering from a cellular proliferation diseasecomprising: administering to the host a composition comprising acontrolled release composition comprising a plurality of solidnanospheres encapsulated in a microsphere formed of a pH sensitive orsalt sensitive matrix material, and a first active agent incorporatedinto at least one of: the nanospheres or the microsphere; wherein saidfirst active agent is selected from the group consisting of a cytotoxicagent, a chemotherapeutic agent, an anti-oncology agent, a radionuclide,a nucleic acid, a protein, and a biopharmaceutical.
 53. A method fortreating a mammal according to claim 52, wherein the mammal has a solidtumor as a result of a cancer selected from the group consisting ofmelanoma, colon cancer, prostate cancer, lung cancer, pancreatic cancer,ovarioan cancer and breast cancer, comprising: administering to themammal an effective amount of a controlled release compositioncomprising a plurality of solid nanospheres encapsulated in amicrosphere formed of a pH sensitive or salt sensitive matrix material,and a first active agent incorporated into at least one of: thenanospheres or the microsphere; wherein said first active agent isselected from the group consisting of a cytotoxic agent, achemotherapeutic agent, an anti-oncology agent, a radionuclide, anucleic acid, a protein, and a biopharmaceutical.
 54. A process forproducing a controlled release composition comprising the steps of:heating a hydrophobic material to a temperature above a melting point toform a hot melt; dissolving or dispersing a first pharmaceutical activeagent into the melt; dissolving or dispersing a second active agent, anda pH sensitive matrix material, in an aqueous phase and heating it toabove the melting temperature of the hydrophobic material; mixing thehot melt with the aqueous phase to form a dispersion; high shearhomogenizing the dispersion at a temperature above the meltingtemperature until a homogeneous fine dispersion is obtained; cooling thedispersion to ambient temperature; and spray drying the emulsified mixedsuspension to form a dry powder composition.